Signal system.



L. A. HAWKINS SIGNAL SYSTEM. APPLICATION FILED NOV. 2, 1908.

Patented June 1,1909.

.ll'lllllllll ullll lnvefv or Laurence A. awkins,

' UNITED STATES PATENT OFFICE.-

.COMPANY, A CORPORATION OF NEW YORK.

SIGNAQL sizs'rnm Specification of Letters Patent.

Patented June 1, 1909.

Application filed November 2, 1908. Serial No. 480,679.

To all whom it may concern:

Signal Systems, of which the following is a specification.

.My invention relates to signal systems for railways, and its object is to provide a novel type. of system which, without the use of track circuits, gives all the protection obtained with the usual track circuit, except ihc indication of a broken rail.

My invention consists in providing means for directing a beam of light across a portion of 'trackto be protected, and a receiver exposed to the light and responsive to variation's therein for controlling a signal, so that a car on that portion of track operates the signal by cutting 01f the light from the receiver. Selenium cells, as is well known,

vary in electrical resistance with variation of light on the cell, so that such cells are well adapled to .beused as receivers in my system.

, My system will best be understood by reference to the ai'zcoinpanying drawings, in which- Figure 1 shows diagrammatically a signal system arrapged in accordance with my invention; Fig. 2 shows a suitable. arrangement of the source of light; Fig. 3 shows a suitable arrangement of the receiver; Fig.4 shows-an intermediate reflector; and Fig. 5 shows a modified arrangement'of the receiver. In Fig. l, A represents the rails of a track, and the dotted lines a represent-the clearance lines of a car on the track B B represent sources of light, the rays from which are. directed across portions of the track by suitable reflecting and focusing means. G G represent reflectors adapted to receive the beamsof light and to reflect them again across other portions of track. D D

represent receivers in the form of selenium cells exposed to thebeams-of light from the sources and reflectors are arranged to direct the beams of light in such manner that a car anywhere on the track between the sources and the cells D I.) will cut off the light from one or the other of the two cells. E represents a battery or other source of current in circuit-with the cells DD, each of which has in series with it 'a relay F. l .he contacts of Itwill be noticed that the- LAURENCE A. HAWKINS, or SGHENEGTADY, NEW YORK, AssieNon o GENERAL ELECTRIC the two relays are in series in the controlling the signal, it cuts off the light from one of the two cells, the resistance of which immediately rises. so as to cause the relay F in series with it to drop its contact, and

thereby to open the signal circuit to put the signal at danger. Until the car has passed the sources B B, one cell or the other is deprived of light by the car, so that the signal remains at danger.

In order that the well directed. each source of light B, which in Fig. 2 is shown as an incandescent lamp, may be provided with a parabolic reflector H and a lens It. In order to prevent the cell D from being afi'ected by the sources of light other than that to which it is intended to respond, it inay be protected by a long tube or hood J, as shown in Fig. 3, while the reflectors C may be provided with similar tubes or hoods, as shown at K in Fig. 4. If these beam of light may be hoods are properly directed the cell can be exposed to a. headlight or other strong light I its own.

In place of usin the arrangement of hoods above describe an arrangement similar to that described inJPatent No. 891,339,

such a case twocells I) D are employed for each beam of light and are placed in circuit with the battery E, and the two opposing windings of a ('liflerential. relay F on a moving train the. cell is protected from disturbance by light from sources other than may be interposed be- "tween the incoming beam and the cell. In

The

polarized light from the source falling'on the prism L is refracted, so as to fall on one only of the cells D I), so. that one coil only of differential relay F is energized. In this case the relay will close its contact. Nonpolarized light, such as would be received from foreign sources, falling on the prism is directed upon both cells D I7. as shown in dotted lilies in Fig. 5, so that both windings of relay I are traversed by current, and there fore neutralize each other, so that the relay contact remains open, as shown in l ig. 5.

It will. of course, be understood that my invention may be utilized for controlling cut section arrangement in track circuit systems.

My invention is particularly advantageous for use in subways or tunnels where the sys tem is not exposed to the weather, or on short lengths of track where the'i'ails are supported on iron ties, as on bridges. where a track circuit cannot conveniently be operated. It is possible to operate long blocks exposed to the weather by the use vot' a powerful source of light and by employing the cutsection arrangement above referred to, precisely as it is employed in track circuit systems to operate a long block where the rail-to-rail resistance is low and track leakage high.

I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appended claims to cover all modifications which are within.

the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In a signal system for railways, a stationary source of light, means for directing the light across a portion of track, a receiver exposed to said light and responsive to variations there n, and a signal controlled by said receiver, whereby a car on said portion of track operates said signal by cutting off the light from said receiver.

2. In a signal system for railways, a.

statio 'iary source of light, means for directing the light. across a portion of track, a selenium cell arranged to receive said light after it has crossed the t 'ack, and a source of current and signal-controlling means in circuit with said cell. v

53.- In a signal system .for railways, a plurality of stationary sources of light, means for directing the light from said sources across different portions of track, a

plurality of receivers for the light from the several sources responsive to variations in light. and a signal controlled by a plurality of said receivers.

4. In a signal system for railways, a plurality of stationary sources of light. means for directing the light from said sources across different portions of track, a plurality of selenium cells arranged to reccivethe light from the several sources, sources of current in circuit with the cells, signal-control]ing means in the, several cell circuits. and a signal controlled by a plurality of said signal'controlling means.

5. In a,sigual system for railways, a stationarv source of light, means for directing the light across a portion of track, a re-' ceiver exposed to said light and responsive to 'ariations therein, a signal controlled by said receiver, and means for preventing light from other sourcesfroin affecting said receiver to control said signal.

(3. Ina signal system for railways. a

stationary source of light, means for directing the light across a portion of track, a

selenium cell arranged to receive said light after it has crossed the track. a source of current in circuit with said cell, signal-controlling Ineans in circuit with said cell, and means for preventing light from other sources from affecting said cell to actuate said signtil-controlling means.

In witness whereof I have hereunto set my hand this 30th day of October, 1908.

LAURENCE A. IIAVVKINS.

W itnesses:

IlnNJAMiN B. IIULL, II icninv ()iiroiin. 

